a span of
A guy who’s got no brains and thinks he’s the king of the world. He probably smells like old socks and doesn’t know how to tie his shoes.
My neighbor is a span-head. He thinks he's the best at everything. He’s wrong.
My friend's brother is a span-head. He can’t even do basic math.
I’m not a span-head. I don’t think I’m the best at everything. I just think I’m really good at it.